[PATCH v2 1/2] exfat: move is_valid_cluster to a common header

[PATCH v2 1/2] exfat: move is_valid_cluster to a common header

[Tadeusz Struk]

Move the is_valid_cluster() helper from fatent.c to a common
header to make it reusable in other *.c files.

Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Sungjong Seo <sj1557.seo@samsung.com>
Cc: linux-fsdevel@vger.kernel.org
Cc: stable@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>
---
 fs/exfat/exfat_fs.h | 6 ++++++
 fs/exfat/fatent.c   | 6 ------
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index c6800b880920..42d06c68d5c5 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -381,6 +381,12 @@ static inline int exfat_sector_to_cluster(struct exfat_sb_info *sbi,
 		EXFAT_RESERVED_CLUSTERS;
 }
 
+static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
+		unsigned int clus)
+{
+	return clus >= EXFAT_FIRST_CLUSTER && clus < sbi->num_clusters;
+}
+
 /* super.c */
 int exfat_set_volume_dirty(struct super_block *sb);
 int exfat_clear_volume_dirty(struct super_block *sb);
diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c
index a3464e56a7e1..421c27353104 100644
--- a/fs/exfat/fatent.c
+++ b/fs/exfat/fatent.c
@@ -81,12 +81,6 @@ int exfat_ent_set(struct super_block *sb, unsigned int loc,
 	return 0;
 }
 
-static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
-		unsigned int clus)
-{
-	return clus >= EXFAT_FIRST_CLUSTER && clus < sbi->num_clusters;
-}
-
 int exfat_ent_get(struct super_block *sb, unsigned int loc,
 		unsigned int *content)
 {
-- 
2.36.1

[PATCH v2 2/2] exfat: check if cluster num is valid

[Tadeusz Struk]

Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap.
This was triggered by reproducer calling truncute with size 0,
which causes the following trace:

BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
Read of size 8 at addr ffff888115aa9508 by task syz-executor251/365

Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x81/0x3c0 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
 exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
 exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181
 __exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217
 exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243
 exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339
 notify_change+0xb76/0xe10 fs/attr.c:336
 do_truncate+0x1ea/0x2d0 fs/open.c:65

Add checks to validate if cluster number is within valid range in
exfat_clear_bitmap() and exfat_set_bitmap()

Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Sungjong Seo <sj1557.seo@samsung.com>
Cc: linux-fsdevel@vger.kernel.org
Cc: stable@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Link: https://syzkaller.appspot.com/bug?id=50381fc73821ecae743b8cf24b4c9a04776f767c
Reported-by: syzbot+a4087e40b9c13aad7892@syzkaller.appspotmail.com
Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>
---
v2:
 - Use is_valid_cluster() helper to validate clu
---
 fs/exfat/balloc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
index 03f142307174..92f5b5b5a0d0 100644
--- a/fs/exfat/balloc.c
+++ b/fs/exfat/balloc.c
@@ -149,6 +149,9 @@ int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
 
 	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
+	if (!is_valid_cluster(sbi, clu))
+		return -EINVAL;
+
 	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
@@ -167,6 +170,9 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
 	struct exfat_mount_options *opts = &sbi->options;
 
 	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
+	if (!is_valid_cluster(sbi, clu))
+		return;
+
 	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
-- 
2.36.1

RE: [PATCH v2 1/2] exfat: move is_valid_cluster to a common header

[Sungjong Seo]

> Move the is_valid_cluster() helper from fatent.c to a common header to
> make it reusable in other *.c files.
> 
> Cc: Namjae Jeon <linkinjeon@kernel.org>
> Cc: Sungjong Seo <sj1557.seo@samsung.com>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: stable@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> 
> Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>

Looks good, thanks for your patch!

Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>

> ---
>  fs/exfat/exfat_fs.h | 6 ++++++
>  fs/exfat/fatent.c   | 6 ------
>  2 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h index
> c6800b880920..42d06c68d5c5 100644
> --- a/fs/exfat/exfat_fs.h
> +++ b/fs/exfat/exfat_fs.h
> @@ -381,6 +381,12 @@ static inline int exfat_sector_to_cluster(struct
> exfat_sb_info *sbi,
>  		EXFAT_RESERVED_CLUSTERS;
>  }
> 
> +static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
> +		unsigned int clus)
> +{
> +	return clus >= EXFAT_FIRST_CLUSTER && clus < sbi->num_clusters; }
> +
>  /* super.c */
>  int exfat_set_volume_dirty(struct super_block *sb);  int
> exfat_clear_volume_dirty(struct super_block *sb); diff --git
> a/fs/exfat/fatent.c b/fs/exfat/fatent.c index a3464e56a7e1..421c27353104
> 100644
> --- a/fs/exfat/fatent.c
> +++ b/fs/exfat/fatent.c
> @@ -81,12 +81,6 @@ int exfat_ent_set(struct super_block *sb, unsigned int
> loc,
>  	return 0;
>  }
> 
> -static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
> -		unsigned int clus)
> -{
> -	return clus >= EXFAT_FIRST_CLUSTER && clus < sbi->num_clusters;
> -}
> -
>  int exfat_ent_get(struct super_block *sb, unsigned int loc,
>  		unsigned int *content)
>  {
> --
> 2.36.1

RE: [PATCH v2 2/2] exfat: check if cluster num is valid

[Sungjong Seo]

> Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap.
> This was triggered by reproducer calling truncute with size 0, which
> causes the following trace:
> 
> BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490
> fs/exfat/balloc.c:174 Read of size 8 at addr ffff888115aa9508 by task syz-
> executor251/365
> 
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]  dump_stack_lvl+0x1e2/0x24b
> lib/dump_stack.c:118
>  print_address_description+0x81/0x3c0 mm/kasan/report.c:233
> __kasan_report mm/kasan/report.c:419 [inline]
>  kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
>  exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
>  exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181
>  __exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217
>  exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243
>  exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339
>  notify_change+0xb76/0xe10 fs/attr.c:336
>  do_truncate+0x1ea/0x2d0 fs/open.c:65
> 
> Add checks to validate if cluster number is within valid range in
> exfat_clear_bitmap() and exfat_set_bitmap()
> 
> Cc: Namjae Jeon <linkinjeon@kernel.org>
> Cc: Sungjong Seo <sj1557.seo@samsung.com>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: stable@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> 
> Link: https://protect2.fireeye.com/v1/url?k=24a746d8-45dcec51-24a6cd97-
> 74fe48600034-8e4653a49a463f3c&q=1&e=0efc824d-6463-4253-9cd7-
> ce3199dbf513&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fbug%3Fid%3D50381fc738
> 21ecae743b8cf24b4c9a04776f767c
> Reported-by: syzbot+a4087e40b9c13aad7892@syzkaller.appspotmail.com
> Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
> Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>

Looks good.
And it seems that WARN_ON() is no longer needed.

Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>

> ---
> v2:
>  - Use is_valid_cluster() helper to validate clu
> ---
>  fs/exfat/balloc.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c index
> 03f142307174..92f5b5b5a0d0 100644
> --- a/fs/exfat/balloc.c
> +++ b/fs/exfat/balloc.c
> @@ -149,6 +149,9 @@ int exfat_set_bitmap(struct inode *inode, unsigned int
> clu, bool sync)
>  	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> 
>  	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
> +	if (!is_valid_cluster(sbi, clu))
> +		return -EINVAL;
> +
>  	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
>  	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
>  	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx); @@ -167,6 +170,9 @@
> void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
>  	struct exfat_mount_options *opts = &sbi->options;
> 
>  	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
> +	if (!is_valid_cluster(sbi, clu))
> +		return;
> +
>  	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
>  	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
>  	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
> --
> 2.36.1

Re: [PATCH v2 2/2] exfat: check if cluster num is valid

[Tadeusz Struk]

On 5/15/22 07:52, Sungjong Seo wrote:
>> Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap.
>> This was triggered by reproducer calling truncute with size 0, which
>> causes the following trace:
>>
>> BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490
>> fs/exfat/balloc.c:174 Read of size 8 at addr ffff888115aa9508 by task syz-
>> executor251/365
>>
>> Call Trace:
>>   __dump_stack lib/dump_stack.c:77 [inline]  dump_stack_lvl+0x1e2/0x24b
>> lib/dump_stack.c:118
>>   print_address_description+0x81/0x3c0 mm/kasan/report.c:233
>> __kasan_report mm/kasan/report.c:419 [inline]
>>   kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
>>   __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
>>   exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
>>   exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181
>>   __exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217
>>   exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243
>>   exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339
>>   notify_change+0xb76/0xe10 fs/attr.c:336
>>   do_truncate+0x1ea/0x2d0 fs/open.c:65
>>
>> Add checks to validate if cluster number is within valid range in
>> exfat_clear_bitmap() and exfat_set_bitmap()
>>
>> Cc: Namjae Jeon<linkinjeon@kernel.org>
>> Cc: Sungjong Seo<sj1557.seo@samsung.com>
>> Cc:linux-fsdevel@vger.kernel.org
>> Cc:stable@vger.kernel.org
>> Cc:linux-kernel@vger.kernel.org
>>
>> Link:https://protect2.fireeye.com/v1/url?k=24a746d8-45dcec51-24a6cd97-
>> 74fe48600034-8e4653a49a463f3c&q=1&e=0efc824d-6463-4253-9cd7-
>> ce3199dbf513&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fbug%3Fid%3D50381fc738
>> 21ecae743b8cf24b4c9a04776f767c
>> Reported-by:syzbot+a4087e40b9c13aad7892@syzkaller.appspotmail.com
>> Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
>> Signed-off-by: Tadeusz Struk<tadeusz.struk@linaro.org>
> Looks good.
> And it seems that WARN_ON() is no longer needed.

Right. Do you want me to send a follow up patch that drops the WARN_ONs?

> Reviewed-by: Sungjong Seo<sj1557.seo@samsung.com>
> 

Thank you.

-- 
Thanks,
Tadeusz

Re: [PATCH v2 2/2] exfat: check if cluster num is valid

[Namjae Jeon]

2022-05-16 23:51 GMT+09:00, Tadeusz Struk <tadeusz.struk@linaro.org>:
> On 5/15/22 07:52, Sungjong Seo wrote:
>>> Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap.
>>> This was triggered by reproducer calling truncute with size 0, which
>>> causes the following trace:
>>>
>>> BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490
>>> fs/exfat/balloc.c:174 Read of size 8 at addr ffff888115aa9508 by task
>>> syz-
>>> executor251/365
>>>
>>> Call Trace:
>>>   __dump_stack lib/dump_stack.c:77 [inline]  dump_stack_lvl+0x1e2/0x24b
>>> lib/dump_stack.c:118
>>>   print_address_description+0x81/0x3c0 mm/kasan/report.c:233
>>> __kasan_report mm/kasan/report.c:419 [inline]
>>>   kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
>>>   __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
>>>   exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
>>>   exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181
>>>   __exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217
>>>   exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243
>>>   exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339
>>>   notify_change+0xb76/0xe10 fs/attr.c:336
>>>   do_truncate+0x1ea/0x2d0 fs/open.c:65
>>>
>>> Add checks to validate if cluster number is within valid range in
>>> exfat_clear_bitmap() and exfat_set_bitmap()
>>>
>>> Cc: Namjae Jeon<linkinjeon@kernel.org>
>>> Cc: Sungjong Seo<sj1557.seo@samsung.com>
>>> Cc:linux-fsdevel@vger.kernel.org
>>> Cc:stable@vger.kernel.org
>>> Cc:linux-kernel@vger.kernel.org
>>>
>>> Link:https://protect2.fireeye.com/v1/url?k=24a746d8-45dcec51-24a6cd97-
>>> 74fe48600034-8e4653a49a463f3c&q=1&e=0efc824d-6463-4253-9cd7-
>>> ce3199dbf513&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fbug%3Fid%3D50381fc738
>>> 21ecae743b8cf24b4c9a04776f767c
>>> Reported-by:syzbot+a4087e40b9c13aad7892@syzkaller.appspotmail.com
>>> Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
>>> Signed-off-by: Tadeusz Struk<tadeusz.struk@linaro.org>
>> Looks good.
>> And it seems that WARN_ON() is no longer needed.
>
> Right. Do you want me to send a follow up patch that drops the WARN_ONs?
You don't need to do it. I have applied this patch to #exfat dev
branch after removing it.
Note that I have combined 1/2 into 2/2 patch.
Thanks!
>
>> Reviewed-by: Sungjong Seo<sj1557.seo@samsung.com>
>>
>
> Thank you.
>
> --
> Thanks,
> Tadeusz
>

Re: [PATCH v2 2/2] exfat: check if cluster num is valid

[Tadeusz Struk]

On 5/16/22 16:31, Namjae Jeon wrote:
>>> Looks good.
>>> And it seems that WARN_ON() is no longer needed.
>> Right. Do you want me to send a follow up patch that drops the WARN_ONs?
> You don't need to do it. I have applied this patch to #exfat dev
> branch after removing it.
> Note that I have combined 1/2 into 2/2 patch.
> Thanks!

That's fine with me. Thanks for taking it.

-- 
Thanks,
Tadeusz